In a variety of computer systems the computer memory can be supplemented with add-on memory systems known as cartridges or plug-in memory modules. Typically these cartridges contain preprogrammed read only memories (ROMs) and are used as a convenient medium for the sale or licensing of popular software packages, including video games.
In video game applications the cartridge memory normally comprises one or more arrays of read only memory which contain both computer instructions and video display data. The computer instructions are processed by the computer and thereby control the placement and movement of display images.
The cartridges for these systems are passive devices in that the computer does all the calculations and controls the selection and timing for fetching data from the cartridge for display on a video system. In these systems the complexity of the game and its display images is limited primarily by the speed and data bandwidth of the computer.
It is therefore a primary object of this invention to provide an improved add-on memory system for increasing the capability of a computer system to execute complex video display oriented computer programs. The add-on memory system is to perform certain functions normally performed by the computer system.
An additional object of the invention is to provide a memory system in accordance with the above objectives that is housed in a plug-in cartridge and can be manufactured at low cost.